Artificial tooth



May 28, 1940. s. MYERSON ARTIFICIAL TOOTH Original Filed Dec. 20, 1937 Patented May 28, 1940 UNITED STATES PATENT OFFICE Application December 20, 1937, Serial No. 180,725 Renewed June 14, 1939 9 Claims., (Cl. 32--9) This invention pertains to artificial teeth or tooth facings of the kind wherein the incisal part at least of the tooth proper, for a substantial distance above the incisal edge, is wholly of a material which transmits light more readily than does the central body and gingival portion of the tooth, thereby very closely simulating natural teeth, as described in the copending applications of SimonMyerson, Serial No. 78,674, filed May 8, 1936, and Serial No. 104,039, filed October 5, 1936.

In anchoring an artificial tooth or tooth facing in place, for example to a bridge, it is customary to employ a metallic supporting member. The facing element of the tooth may be secured to this supporting member by means of akey-to-keyway joint and cementation, or by means of a pin or pins with or without solder. In plate-work it is usual to terminate the supporting member at a substantial distance from the incisal portion of the tooth, and under such circumstances the arrangement specifically disclosed in the aforesaid copending applications is desirable and adequate, since there is nothing at the lingual side of the incisal portion of the tooth to modify the desired effects resulting from the transparency of such edge. However, for certain uses it is desirable to extend the backing or supporting member down substantially to the incisal edge, for instance, to reinforce the edge portion of the tooth. When a backing of opaque material (for example metal) is thus extended down to the incisal edge, the color of the backing, for instance yellow gold, may seriously impair, if not wholly nullify, the advantages derived from the use of the transparent edge material.

One object of the present invention is toprovide an artificial tooth, or a facing member therefor, having the incisal edge portion of a material which transmits light more readily than the central body portion of the tooth and wherein the backing extends substantially to the incisal edge, but having provision for so masking the effect of the backing member as substantially to preserve or at least to simulate the beneficial effects which are normally obtained by the use of an unbacked incisal edge of translucent or transparent material.

Natural teeth are not of uniform color nor are the incisal edge portions of natural teeth (consisting almost wholly of enamel) exactly uniform in color, thickness or texture. As a matter of fact, the labial surface, and in particular the incisal portion of a natural tooth usually has narrow, more or less parallel, darker lines or stains extending substantially perpendicular to the incisal edge, that is to say. lengthwise of the tooth. These narrow lines usually result from the presence of fine cracks in the enamel.

A further object of the invention is to provide a tooth or a tooth facing such as may be manufactured in finished form by mass production methods and which is so constructed that, when viewed against the dark background of the oral cavity, it exhibits narrow streaks or shadow lines closely simulating those of natural teeth, the streak-forming material being a permanent part of the tooth structure incorporated during manufacture.

Other'and further objects and advantages of the invention will be pointed out in'the following 5 more detailed description and by reference to the accompanying drawing, wherein Fig. l is a front or labial elevation of an artificial anterior tooth embodying features of the present invention, the tooth being shown to very large scale;

Fig. 2 is a section substantially on the line 2-2 of Fig. 1;

Fig. 3 is a section substantially on the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary section, to larger scale, on line 44 of Fig. 1;

Fig. 5 is a view similar to Fig. 1, but having portions of the tooth broken away to show the internal construction;

Fig. 6 is a view similar to Fig. 2, but illustrating a modification;

Fig. 7 is a perspective view, to very large size, illustrating an elongate piece of material such as may be employed to produce a striation in the tooth; and I Fig. 8 is a view similar to Fig. 2 but illustrating a different form of tooth and backing member.

Referring to the drawing, the numeral l designates the central or body portion of the tooth or tooth facing. such body portion being made of the usual ceramic material and having its front or labial surface 2 covered with enamel 3. As indicated in Fig. 2. this enamel extends down to a point well below the extreme lower edge l of the opaque body portion to form the incisal edge 4, the rear or lingual face 5 of this downwardly directed mass of enamel being of appreciable vertical extent, for instance, one-sixth or more of the total depth of the tooth. The enamel also extends laterally. as shown at 6 and 1 (Fig. 1), to points above the extreme lower edge l of the body portion, thus providing an incisal marginal portion of substantial depth consisting wholly of enamel. This enamel is of a material which transmits light much more freely than does-the.

tinct area of substantial. depth which is quite translucent or even transparent.

The facing member (comprising the body por-, tion I and the enamel) is secured, as shown in Fig. 2, by means of a pin I I to a supporting mem-. her 8 which may be of any suitable and/or usual material. As shown in Fig. 2, the supporting member 8 extendsfrom the gingival surfaced of the tooth down to the point ID, with its lower edge substantially flush with the incisal edge]? of the tooth facing. Since the body of enamel at the incisal edge is of substantial vertical depth,- as indicated at 5, the lower part I lot the supporting member would be more orless visible through this transparent incisal margin .of the tooth and would thus impart its own'color or appearance to the lower portion of the were some means not taken to prevent it.

In accordance 'with the present invention,- and in order to prevent this undesired color effect of the supporting member material, a masking layer I2 is interposed between the body portion I and the supporting member 8. This masking layer I2 is of any suitable material having the'deslred characteristics, for example a layer [of very opaque ceramic material. 'I'his'layer- .-I2 'pref erably is secured'to thetooth (comprising the parts I and 3) to form an integralportion thereof, and its color or other physical characteristics are such that when viewed through the transparent incisal margin of the tooth, substantially the same effect results as though a tooth of type, but without the support 8, were viewed against the dark background of the. oral cavity. To obtain'this effect,

this layer I2 is preferably ofsomegn'eutr'al shade,

for example grayjand in order thatit' may'f-be of high light-dispersive and absorptive qualityjthusto avoid reflection from it's forward surface, is preferred, as shown in Fig. 5, to give'the labial face of this layer I2 a'mat surface I2.

While it may be more simple to have the mask-.

ing layer I2 extend over the entire lingual surface of the'tooth facing, it may, under some circumstances, be preferred tolimit the layer I2 substantially to the exposed lingual surface'of the transparent enamel 3 where the latter projects beyond the lower edge of the body portion I.

Thus, as illustrated in Fig. 6, wherein the tooth facing is shown as united to the support 8* by a key II and keyway IN, the layer I2 of masking material covers only the surface 5 of the enamel, while at the upper part of the tooth the support 8 contacts directly with the rear surface of the body portion of the tooth. 1

In Fig. 8 the invention is illustrated as embodled in a tooth of somewhat different form from that of l. 2 and 3-the-labial face of the tooth having. angularly disposed faces for engagement by corresponding surfaces ,of a metallic supporting member 8, to which the porcelain portion of the tooth is secured by means of apin -II=' interposed between the vertical part III of this metal plate and the transparent incisal margin of the tooth is a masking layer I2 of a material similar to that of the layer I 2 above described.

In accordance with the present invention, it is also proposed to form the front or labial surface of the tooth so as even better to simulate a natural tooth by the inclusion of narrow streaks and stains of a colcr or appearance which visually contrasts with that of the enamel and simulates tooth el layer, (and -and in general substantially perpendicular. to

such edge. As illustrated in-Fig. 1 these inserts may extend upwardly beyond the lower edge of sert is in front of the body portion and projects forwardly from the latter into the layer of enam- .er which overlies the'labial surface of the body -;-portion, The intended effect of these inserts. at leastat the translucent incisalportion of the tooth, is dependent upon the presence of a dark -background (for example the oral cavity, or a proper masking for the supporting member) against which to view the more-or less transparent incisal portion of the-tooth.

In order to obtain-the most desirable effects, it has 'beenfound that these inserts I3 should have. very narrowv forward .edges ,1 preferably approaching a knife edge in sharpness and that these edges should preferably lie substantially inthe plane of the outer surface of. the enamel] Preferably these inserts I3 take the form of eiongate, triangular prisms, desirably of slightly irregular contour so'as better to "simulate the irregular striations of the natural "tooth. As already stated, these inserts I3 contrast visually in appearancewith the enamel; for. example, they may be madeof deeply colored material or a material which differs in opacity from the enamel, and one or more of such inserts may be embedded in the enamel of the tooth so as to become fused'or otherwise permanently integrated with the enamel, the'operation of embeddingthe inserts in the enamel-forming material during the packing of the tooth'mould-producing narrow, elongate grooves,'crevices or fissures extending forwardly toward-the labial surface of the enamwhich are completely filled by the inserts; I i

If-desired, the inserts I3 may beof a color different from that of the body portion I and, by makingthem of triangular contour, a more or less indistinct or shadow effect is produced which seems more closely to simulate the natural tooth than though the insert be of uniform thickness. However, it' is contemplated that inserts of other than triangular transverse section may be employed if desired. For convenience in description and in the 'clainis reference has been made to the upper and lower parts of the tooth, the tooth illustrated in the drawing having its gingival surface uppermost, but it is to be understood that 'such use of the terms upper", lower' etc. is merely relative and that the invention is not in any way limited to teeth positioned as specifically,

shown in the drawing.

While I have herein disclosed-certain desirable embodiments of the invention by way'of example, it is to be understood that the invention is not necessarily limited to these precise embodiments but is to be regarded as broadly inclusive of any and all equivalent arrangements whereby the improved results are obtained.

I claim:

1. An-artifleialtooth of the kind having a' body portion of'relatively opaque material which constitutes th major part of the tooth, a mass of relatively transparent enamel constituting the 10 I the body portion so that the upper part of the in incisal portion of the tooth and terminating at 1 the incisal edge, and a supporting member disposed at the lingual side of the body portion and which extends downwardly to the incisal edge,

characterized in that the incisal portion extends downwardly below the lower end of the body portion to a distance such as to provide a light-trans mitting area of substantial depth which would appear darker than the body of the tooth if viewed from the front against the background of the oral cavity, and further characterized in having light-absorbing and diffusing means interposed between the supporting member and said light-transmitting incisal portion, said light-abwhich extends downwardly to the incisal edge,

characterized in that said mass of enamel has an upward extension overlying the lower part at least of the labial surface of the body portion, the enamel mass extending down below the lower end of the body portion a distance substantially exceeding the maximum front-to-rear thickness of said upward extension, and further characterized in having interposed between the support and the.

lingual surface of the relatively transparent incisal portion a layer of ceramic material of a neutral color and having a mat-finished labial surface operative to absorb and diffuse light falling thereon thereby to conceal the support and simulate the effect of the darkness of the oral cavity when the tooth is viewed from the front.

3. An artificial tooth of the kind wherein a body portion of relatively opaque material is provided with an incisal portion of relatively transparent enamel extending down below the lower edge of the body portion and wherein a supporting member is united to the body portion and extends downwardly to a point substantially flush with the incisal edge of the tooth, characterized in having means masking the backing material, said masking material being interposed between the supporting member and incisal margin and being of a character to simulate the darkness of the oral cavity when viewed through the incisal portion, and means embedded in the incisal portion designed and arranged to simulate the relatively opaque striations and stains commonly occurring in the incisal portion of a natural tooth.

4. An artificial tooth of the kind having a body portion of a relatively opaque material and having its labial surface of a relatively transparent enamel which is fused to and which extends down below the lower edge of the body portion to form an incisal margin of the transparent material, and an elongate, narrow, relatively opaque insert embedded in and fused with the enamel forming said incisal portion, said insert being initially separate, preformed and distinct from the body portion and enamel layer and being of substantially wedge-shape in transverse section and having a very thin labial edge substantially flush with the labial surface of the enamel, said insert. increasing in width rearwardly from the labiaflsurface of--the enamel.

5. An artificial tooth of the kind having a body portion of relatively opaque material having fused to its labial surface a layer of relatively transparent enamel which continues down below the lower edge of the body portion and merges with an incisal mass of enamel, and an elongate preformed narrow insert of ceramic material embedded in and fused with said enamel, said insert being initially separate and distinct from the body portion and enamel layer and having a thin forward edge, one end portion at least of said insert being fused to and projecting forwardly from the body portion of the tooth, said insert increasing in thickness rearwardly from said edge and contrasting in appearance with that of the enamel, the thin forward edge of the insert being substantially flush with the labial outer surface of the enamel thereby to produce the effect of a stria at the labial faceof the tooth.

6. An artificial tooth of the kind in which the body portion has a layer of enamel fused to its labial surface, characterized in having a preformed elongate narrow insert of a material which difiers in optical properties from the enamel layer embedded in and fused with said enamel layer, said insert being initially separate and distinct from the body portion and enamel layer and having a thin forward edge substantially flush with the outer surface of the enamel thereby to produce the effect of a stria at the outer surface of the tooth.-

7. An artificial tooth of the kind having a body portion of relatively opaque material which constitutes the major part of the tooth, and a mass of relatively transparent enamel constituting the 'incisal portion of the tooth and terminating at the incisal edge, said enamel mass extending up toward the gingival surface of the tooth to form a labial surface layer which is fused to the body portion, characterized in that said incisal mass of enamel extends downwardly below the lower end of the body portion to a distance such as to provide a light-transmitting area of substantial depth which appears darker than the body' of the tooth when viewed from the front against the background of the oral cavity, and further characterized in having an elongate preformed insert of ceramic material, initially separate and distinct from the body portion and enamel, which extends lengthwise of the tooth and which is embedded in and fused with said enamel, said insert having a thin forward edge which is substantially flush with the outer surface of said enamel, the insert being of a distinctive visual appearance contrasting with the enamel thereby to produce the effect of a stria at the labial face of the tooth.

8. An artificial tooth of the kind in which the body portion has a layer of enamel fused to its labial surface, characterized in having an elongate insert embedded in said enamel layer, said insert differing in optical properties from the enamel layer and being of substantially triangular transverse section with one acute longitudinal edge thereof disposed substantially in the labial surface of the enamel layer and with its lateral faces diverging rearwardly from said edge within the substance of the enamel whereby light which enters through the enamel is reflected toward the observer with varying effect from surfaces of the insert which are inclined to the labial face of the tooth, said enamel, insert and body portion being interfused with each other.

9. In combination in an artificial tooth, an enamel layer having a concave lingual faceand a convex labial face, said enamel layer being designed to constitute the labial, mesial and distal surfaces of the artificial tooth, and an elongate separate and distinct insert of ceramic material differing in optical properties from the enamel layer and designed to simulate one of the longitudinal stria commonly occurring in natural teeth, said insert being embedded in the concave face of the enamel layer and fused with the 10 enamel, the insert being substantially wedgeshape in transverse section with its acute forward edge substantially flush with the labial surface of the enamel layer and with its lateral faces diverging rearwardly within the substance of the enamel whereby light which enters through the enamel is reflected toward the observer with anintensity which progressively decreases laterally from said edge of the insert.

DISCLAIMER 2,202,713.Sim0n Zllyerson, Brookline, Mass. ARTIFICIAL TOOTH. Patent dated May 28, 1940. Disclaimer filed Mar. 28, 1947, by the inventor. Hereby enters this disclaimer to claims 8 and 9 of said patent.

[Ofiicial Gazette Apnl 29, 1.947.] 

